This invention relates to the processing of electrical signals, particularly to the conversion of analog input signals, having amplitudes varying in response to various stimuli, into output signals having frequencies determined by the characteristics of the input signals. The invention further relates to the measurement over time of forces and moments, and the generation and processing of electrical signals corresponding to the measured forces and moments. The invention also relates to electronic ski binding systems wherein a safety binding may be placed in a releasing condition from a locking condition upon the generation of electrical signals indicative of forces or moments that may injure a skier.
Electrical circuits incorporating sensors, transducers, and other signal sources produce analog electrical signals, that is, signals having amplitudes indicative of the magnitudes of various stimuli. The evaluation of the cumulative effect of these stimuli for generation of responses requires the measurement of these input signals over time. Processing of such signals by fixed parameter digital and analog techniques is known in the art. Such digital techniques commonly employ analog-to-digital signal conversion circuitry to convert the analog input signals to a digital form suitable for processing in digital circuitry. Typically, both digital and analog techniques for measurement over time, e.g., integration, of signals, use fixed integration parameters.
Because of the advantages digital signal processing offers in comparison to analog signal processing, it is desirable that a digital system with variable parameters be available. However, in many applications it is not desirable to use circuitry employing analog-to-digital signal converter circuits because of their relative high cost and power consumption. These disadvantages are particularly felt in consumer products, especially in those which must have a remote power source. An example is a battery-powered electronic ski binding, that is, a ski binding where the forces and/or moments between a ski and a skier's boot are electrically measured to generate corresponding signals. The signals are processed to determine whether or not to generate a trigger signal to actuate the release means of the binding. The release means switches the binding mechanism from its latching condition, in which the boot is firmly grasped, to the releasing condition, in which the boot is released from the binding.
It is known in the art to convert an analog electrical signal into an output signal having a frequency proportional to the amplitude of the analog signal. The cumulative effect of the input signal may then be measured by counting and accumulating the number of cycles of output signal generated using conventional digital counter circuitry. For an example, see Titus, et al., Microcomputer-Analog Converter Software and Hardware Interfacing (Howard W. Sams & Co. 1978) pp. 117-120. This known circuitry avoids the use of an analog-to-digital signal converter in achieving fixed parameter digital integration.